Ruellia eriocalyx, T. F. Daniel, E. Tripp & C. Ezcurra

Daniel, Thomas F., Manzitto-Tripp, Erin A. & Ezcurra, Cecilia, 2023, Ruellia eriocalyx (Acanthaceae, Ruellieae), a Pyrophytic Species from Central Brazil, Proceedings of the California Academy of Sciences 67 (17), pp. 395-399 : 398

The following key distinguishes Ruellia eriocalyx from its morphologically similar congener(s):

1a. Roots with fusiform-tuberous swellings; plants subcaulescent to caulescent, to 30 cm high; bracteoles present and conspicuous (more than 10 mm long); dichasia mostly 1-flowered, sessile (or borne on peduncles less than 5 mm long), flowers sessile; corollas pale blue, (35–) 50–70 mm long; capsules 12–15 mm long; central to southern Brazil, eastern Paraguay, and eastern Argentina......................... R. dissitifolia / R. brevicaulis (Nees) Lindau

1b. Roots thickened but not with fusiform-tuberous swellings; plants subcaulescent, to 10 cm high; bracteoles absent (or inconspicuous; if present, not seen); flowers borne on pedicels (2.5–) 7–42 mm long; corollas purplish, (30–) 40–56 mm long; capsules 9-11 mm long; central Brazil (Distrito Federal, Goías)............................................ R. eriocalyx